<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>getElementsByTagName</title>
</head>
<body>
        <ul>
            <li>今天</li>
            <li>明天</li>
            <li>昨天</li>
            <li>前天</li>
            <li>每天</li>
        </ul>
        <script>
            console.log(document.getElementsByTagName('li'));          //读取li
            console.log(document.getElementsByTagName('li')[0]);       //读取li中的一个
        </script>
</body>
</html>